Ue multiplexing for dmrs transmission

ABSTRACT

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a UE. The UE receives an indication for transmitting a particular DMRS sequence in an uplink transmission. The particular DMRS sequence is time domain based. The UE determines an adjustment to a base DMRS sequence for generating the particular DMRS sequence. The UE generates the particular DMRS sequence based on the adjustment and the base DMRS sequence. The UE modulates the particular DMRS sequence to obtain a set of symbols. The UE maps a plurality of symbols of the set of symbols to a plurality of subcarriers. The UE transmits the plurality of symbols on the plurality of subcarriers.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefits of U.S. Provisional ApplicationSer. No. 62/791,116, entitled “LOW PAPR REFERENCE SIGNAL FOR π/2-BPSKDFT-S-OFDM” and filed on Jan. 11, 2019; U.S. Provisional ApplicationSer. No. 62/801,637, entitled “LOW PAPR REFERENCE SIGNAL FOR DFT-S-OFDM”and filed on Feb. 5, 2019; U.S. Provisional Application Ser. No.62/806,016, entitled “LOW PAPR REFERENCE SIGNAL FOR π/2-BPSK DFT-S-OFDM”and filed on Feb. 15, 2019; U.S. Provisional Application Ser. No.62/817,663, entitled “UE MULTIPLEXING FOR π/2-BPSK DMRS TRANSMISSION”and filed on Mar. 13, 2019; all of which are expressly incorporated byreference herein in their entirety.

BACKGROUND Field

The present disclosure relates generally to communication systems, andmore particularly, to techniques of generating and transmittingdemodulation reference signals (DMRSs).

Background

The statements in this section merely provide background informationrelated to the present disclosure and may not constitute prior art.

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources. Examples of suchmultiple-access technologies include code division multiple access(CDMA) systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, orthogonal frequency divisionmultiple access (OFDMA) systems, single-carrier frequency divisionmultiple access (SC-FDMA) systems, and time division synchronous codedivision multiple access (TD-SCDMA) systems.

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. An example telecommunication standardis 5G New Radio (NR). 5G NR is part of a continuous mobile broadbandevolution promulgated by Third Generation Partnership Project (3GPP) tomeet new requirements associated with latency, reliability, security,scalability (e.g., with Internet of Things (IoT)), and otherrequirements. Some aspects of 5G NR may be based on the 4G Long TermEvolution (LTE) standard. There exists a need for further improvementsin 5G NR technology. These improvements may also be applicable to othermulti-access technologies and the telecommunication standards thatemploy these technologies.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

In an aspect of the disclosure, a method, a computer-readable medium,and an apparatus are provided. The apparatus may be a UE. The UEreceives an indication for transmitting a particular DMRS sequence in anuplink transmission. The particular DMRS sequence is time domain based.The UE determines an adjustment to a base DMRS sequence for generatingthe particular DMRS sequence. The UE generates the particular DMRSsequence based on the adjustment and the base DMRS sequence. The UEmodulates the particular DMRS sequence to obtain a set of symbols. TheUE maps a plurality of symbols of the set of symbols to a plurality ofsubcarriers. The UE transmits the plurality of symbols on the pluralityof subcarriers.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network.

FIG. 2 is a diagram illustrating a base station in communication with aUE in an access network.

FIG. 3 illustrates an example logical architecture of a distributedaccess network.

FIG. 4 illustrates an example physical architecture of a distributedaccess network.

FIG. 5 is a diagram showing an example of a DL-centric subframe.

FIG. 6 is a diagram showing an example of an UL-centric subframe.

FIG. 7 is a diagram illustrating communications between a base stationand UE.

FIG. 8 is a flow chart of a method (process) for generating andtransmitting a DMRS sequence.

FIG. 9 is a conceptual data flow diagram illustrating the data flowbetween different components/means in an exemplary apparatus.

FIG. 10 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented withreference to various apparatus and methods. These apparatus and methodswill be described in the following detailed description and illustratedin the accompanying drawings by various blocks, components, circuits,processes, algorithms, etc. (collectively referred to as “elements”).These elements may be implemented using electronic hardware, computersoftware, or any combination thereof. Whether such elements areimplemented as hardware or software depends upon the particularapplication and design constraints imposed on the overall system.

By way of example, an element, or any portion of an element, or anycombination of elements may be implemented as a “processing system” thatincludes one or more processors. Examples of processors includemicroprocessors, microcontrollers, graphics processing units (GPUs),central processing units (CPUs), application processors, digital signalprocessors (DSPs), reduced instruction set computing (RISC) processors,systems on a chip (SoC), baseband processors, field programmable gatearrays (FPGAs), programmable logic devices (PLDs), state machines, gatedlogic, discrete hardware circuits, and other suitable hardwareconfigured to perform the various functionality described throughoutthis disclosure. One or more processors in the processing system mayexecute software. Software shall be construed broadly to meaninstructions, instruction sets, code, code segments, program code,programs, subprograms, software components, applications, softwareapplications, software packages, routines, subroutines, objects,executables, threads of execution, procedures, functions, etc., whetherreferred to as software, firmware, middleware, microcode, hardwaredescription language, or otherwise.

Accordingly, in one or more example embodiments, the functions describedmay be implemented in hardware, software, or any combination thereof. Ifimplemented in software, the functions may be stored on or encoded asone or more instructions or code on a computer-readable medium.Computer-readable media includes computer storage media. Storage mediamay be any available media that can be accessed by a computer. By way ofexample, and not limitation, such computer-readable media can comprise arandom-access memory (RAM), a read-only memory (ROM), an electricallyerasable programmable ROM (EEPROM), optical disk storage, magnetic diskstorage, other magnetic storage devices, combinations of theaforementioned types of computer-readable media, or any other mediumthat can be used to store computer executable code in the form ofinstructions or data structures that can be accessed by a computer.

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network 100. The wireless communications system(also referred to as a wireless wide area network (WWAN)) includes basestations 102, UEs 104, and a core network 160. The base stations 102 mayinclude macro cells (high power cellular base station) and/or smallcells (low power cellular base station). The macro cells include basestations. The small cells include femtocells, picocells, and microcells.

The base stations 102 (collectively referred to as Evolved UniversalMobile Telecommunications System (UMTS) Terrestrial Radio Access Network(E-UTRAN)) interface with the core network 160 through backhaul links132 (e.g., S1 interface). In addition to other functions, the basestations 102 may perform one or more of the following functions:transfer of user data, radio channel ciphering and deciphering,integrity protection, header compression, mobility control functions(e.g., handover, dual connectivity), inter-cell interferencecoordination, connection setup and release, load balancing, distributionfor non-access stratum (NAS) messages, NAS node selection,synchronization, radio access network (RAN) sharing, multimediabroadcast multicast service (MBMS), subscriber and equipment trace, RANinformation management (RIM), paging, positioning, and delivery ofwarning messages. The base stations 102 may communicate directly orindirectly (e.g., through the core network 160) with each other overbackhaul links 134 (e.g., X2 interface). The backhaul links 134 may bewired or wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Eachof the base stations 102 may provide communication coverage for arespective geographic coverage area 110. There may be overlappinggeographic coverage areas 110. For example, the small cell 102′ may havea coverage area 110′ that overlaps the coverage area 110 of one or moremacro base stations 102. A network that includes both small cell andmacro cells may be known as a heterogeneous network. A heterogeneousnetwork may also include Home Evolved Node Bs (eNBs) (HeNBs), which mayprovide service to a restricted group known as a closed subscriber group(CSG). The communication links 120 between the base stations 102 and theUEs 104 may include uplink (UL) (also referred to as reverse link)transmissions from a UE 104 to a base station 102 and/or downlink (DL)(also referred to as forward link) transmissions from a base station 102to a UE 104. The communication links 120 may use multiple-input andmultiple-output (MIMO) antenna technology, including spatialmultiplexing, beamforming, and/or transmit diversity. The communicationlinks may be through one or more carriers. The base stations 102/UEs 104may use spectrum up to Y MHz (e.g., 5, 10, 15, 20, 100 MHz) bandwidthper carrier allocated in a carrier aggregation of up to a total of YxMHz (x component carriers) used for transmission in each direction. Thecarriers may or may not be adjacent to each other. Allocation ofcarriers may be asymmetric with respect to DL and UL (e.g., more or lesscarriers may be allocated for DL than for UL). The component carriersmay include a primary component carrier and one or more secondarycomponent carriers. A primary component carrier may be referred to as aprimary cell (PCell) and a secondary component carrier may be referredto as a secondary cell (SCell).

The wireless communications system may further include a Wi-Fi accesspoint (AP) 150 in communication with Wi-Fi stations (STAs) 152 viacommunication links 154 in a 5 GHz unlicensed frequency spectrum. Whencommunicating in an unlicensed frequency spectrum, the STAs 152/AP 150may perform a clear channel assessment (CCA) prior to communicating inorder to determine whether the channel is available.

The small cell 102′ may operate in a licensed and/or an unlicensedfrequency spectrum. When operating in an unlicensed frequency spectrum,the small cell 102′ may employ NR and use the same 5 GHz unlicensedfrequency spectrum as used by the Wi-Fi AP 150. The small cell 102′,employing NR in an unlicensed frequency spectrum, may boost coverage toand/or increase capacity of the access network.

The gNodeB (gNB) 180 may operate in millimeter wave (mmW) frequenciesand/or near mmW frequencies in communication with the UE 104. When thegNB 180 operates in mmW or near mmW frequencies, the gNB 180 may bereferred to as an mmW base station. Extremely high frequency (EHF) ispart of the RF in the electromagnetic spectrum. EHF has a range of 30GHz to 300 GHz and a wavelength between 1 millimeter and 10 millimeters.Radio waves in the band may be referred to as a millimeter wave. NearmmW may extend down to a frequency of 3 GHz with a wavelength of 100millimeters. The super high frequency (SHF) band extends between 3 GHzand 30 GHz, also referred to as centimeter wave. Communications usingthe mmW/near mmW radio frequency band has extremely high path loss and ashort range. The mmW base station 180 may utilize beamforming 184 withthe UE 104 to compensate for the extremely high path loss and shortrange.

The core network 160 may include a Mobility Management Entity (MME) 162,other MMEs 164, a Serving Gateway 166, a Multimedia Broadcast MulticastService (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC)170, and a Packet Data Network (PDN) Gateway 172. The MME 162 may be incommunication with a Home Subscriber Server (HSS) 174. The MME 162 isthe control node that processes the signaling between the UEs 104 andthe core network 160. Generally, the MME 162 provides bearer andconnection management. All user Internet protocol (IP) packets aretransferred through the Serving Gateway 166, which itself is connectedto the PDN Gateway 172. The PDN Gateway 172 provides UE IP addressallocation as well as other functions. The PDN Gateway 172 and the BM-SC170 are connected to the IP Services 176. The IP Services 176 mayinclude the Internet, an intranet, an IP Multimedia Subsystem (IMS), aPS Streaming Service (PSS), and/or other IP services. The BM-SC 170 mayprovide functions for MBMS user service provisioning and delivery. TheBM-SC 170 may serve as an entry point for content provider MBMStransmission, may be used to authorize and initiate MBMS Bearer Serviceswithin a public land mobile network (PLMN), and may be used to scheduleMBMS transmissions. The MBMS Gateway 168 may be used to distribute MBMStraffic to the base stations 102 belonging to a Multicast BroadcastSingle Frequency Network (MBSFN) area broadcasting a particular service,and may be responsible for session management (start/stop) and forcollecting eMBMS related charging information.

The base station may also be referred to as a gNB, Node B, evolved NodeB (eNB), an access point, a base transceiver station, a radio basestation, a radio transceiver, a transceiver function, a basic serviceset (BSS), an extended service set (ESS), or some other suitableterminology. The base station 102 provides an access point to the corenetwork 160 for a UE 104. Examples of UEs 104 include a cellular phone,a smart phone, a session initiation protocol (SIP) phone, a laptop, apersonal digital assistant (PDA), a satellite radio, a globalpositioning system, a multimedia device, a video device, a digital audioplayer (e.g., MP3 player), a camera, a game console, a tablet, a smartdevice, a wearable device, a vehicle, an electric meter, a gas pump, atoaster, or any other similar functioning device. Some of the UEs 104may be referred to as IoT devices (e.g., parking meter, gas pump,toaster, vehicles, etc.). The UE 104 may also be referred to as astation, a mobile station, a subscriber station, a mobile unit, asubscriber unit, a wireless unit, a remote unit, a mobile device, awireless device, a wireless communications device, a remote device, amobile subscriber station, an access terminal, a mobile terminal, awireless terminal, a remote terminal, a handset, a user agent, a mobileclient, a client, or some other suitable terminology.

FIG. 2 is a block diagram of a base station 210 in communication with aUE 250 in an access network. In the DL, IP packets from the core network160 may be provided to a controller/processor 275. Thecontroller/processor 275 implements layer 3 and layer 2 functionality.Layer 3 includes a radio resource control (RRC) layer, and layer 2includes a packet data convergence protocol (PDCP) layer, a radio linkcontrol (RLC) layer, and a medium access control (MAC) layer. Thecontroller/processor 275 provides RRC layer functionality associatedwith broadcasting of system information (e.g., MIB, SIBs), RRCconnection control (e.g., RRC connection paging, RRC connectionestablishment, RRC connection modification, and RRC connection release),inter radio access technology (RAT) mobility, and measurementconfiguration for UE measurement reporting; PDCP layer functionalityassociated with header compression/decompression, security (ciphering,deciphering, integrity protection, integrity verification), and handoversupport functions; RLC layer functionality associated with the transferof upper layer packet data units (PDUs), error correction through ARQ,concatenation, segmentation, and reassembly of RLC service data units(SDUs), re-segmentation of RLC data PDUs, and reordering of RLC dataPDUs; and MAC layer functionality associated with mapping betweenlogical channels and transport channels, multiplexing of MAC SDUs ontotransport blocks (TBs), demultiplexing of MAC SDUs from TBs, schedulinginformation reporting, error correction through HARQ, priority handling,and logical channel prioritization.

The transmit (TX) processor 216 and the receive (RX) processor 270implement layer 1 functionality associated with various signalprocessing functions. Layer 1, which includes a physical (PHY) layer,may include error detection on the transport channels, forward errorcorrection (FEC) coding/decoding of the transport channels,interleaving, rate matching, mapping onto physical channels,modulation/demodulation of physical channels, and MIMO antennaprocessing. The TX processor 216 handles mapping to signalconstellations based on various modulation schemes (e.g., binaryphase-shift keying (BPSK), quadrature phase-shift keying (QPSK),M-phase-shift keying (M-PSK), M-quadrature amplitude modulation(M-QAM)). The coded and modulated symbols may then be split intoparallel streams. Each stream may then be mapped to an OFDM subcarrier,multiplexed with a reference signal (e.g., pilot) in the time and/orfrequency domain, and then combined together using an Inverse FastFourier Transform (IFFT) to produce a physical channel carrying a timedomain OFDM symbol stream. The OFDM stream is spatially precoded toproduce multiple spatial streams. Channel estimates from a channelestimator 274 may be used to determine the coding and modulation scheme,as well as for spatial processing. The channel estimate may be derivedfrom a reference signal and/or channel condition feedback transmitted bythe UE 250. Each spatial stream may then be provided to a differentantenna 220 via a separate transmitter 218TX. Each transmitter 218TX maymodulate an RF carrier with a respective spatial stream fortransmission.

At the UE 250, each receiver 254RX receives a signal through itsrespective antenna 252. Each receiver 254RX recovers informationmodulated onto an RF carrier and provides the information to the receive(RX) processor 256. The TX processor 268 and the RX processor 256implement layer 1 functionality associated with various signalprocessing functions. The RX processor 256 may perform spatialprocessing on the information to recover any spatial streams destinedfor the UE 250. If multiple spatial streams are destined for the UE 250,they may be combined by the RX processor 256 into a single OFDM symbolstream. The RX processor 256 then converts the OFDM symbol stream fromthe time-domain to the frequency domain using a Fast Fourier Transform(FFT). The frequency domain signal comprises a separate OFDM symbolstream for each subcarrier of the OFDM signal. The symbols on eachsubcarrier, and the reference signal, are recovered and demodulated bydetermining the most likely signal constellation points transmitted bythe base station 210. These soft decisions may be based on channelestimates computed by the channel estimator 258. The soft decisions arethen decoded and deinterleaved to recover the data and control signalsthat were originally transmitted by the base station 210 on the physicalchannel. The data and control signals are then provided to thecontroller/processor 259, which implements layer 3 and layer 2functionality.

The controller/processor 259 can be associated with a memory 260 thatstores program codes and data. The memory 260 may be referred to as acomputer-readable medium. In the UL, the controller/processor 259provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, and control signalprocessing to recover IP packets from the core network 160. Thecontroller/processor 259 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

Similar to the functionality described in connection with the DLtransmission by the base station 210, the controller/processor 259provides RRC layer functionality associated with system information(e.g., MIB, SIBs) acquisition, RRC connections, and measurementreporting; PDCP layer functionality associated with headercompression/decompression, and security (ciphering, deciphering,integrity protection, integrity verification); RLC layer functionalityassociated with the transfer of upper layer PDUs, error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC SDUs,re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; andMAC layer functionality associated with mapping between logical channelsand transport channels, multiplexing of MAC SDUs onto TBs,demultiplexing of MAC SDUs from TBs, scheduling information reporting,error correction through HARQ, priority handling, and logical channelprioritization.

Channel estimates derived by a channel estimator 258 from a referencesignal or feedback transmitted by the base station 210 may be used bythe TX processor 268 to select the appropriate coding and modulationschemes, and to facilitate spatial processing. The spatial streamsgenerated by the TX processor 268 may be provided to different antenna252 via separate transmitters 254TX. Each transmitter 254TX may modulatean RF carrier with a respective spatial stream for transmission. The ULtransmission is processed at the base station 210 in a manner similar tothat described in connection with the receiver function at the UE 250.Each receiver 218RX receives a signal through its respective antenna220. Each receiver 218RX recovers information modulated onto an RFcarrier and provides the information to a RX processor 270.

The controller/processor 275 can be associated with a memory 276 thatstores program codes and data. The memory 276 may be referred to as acomputer-readable medium. In the UL, the controller/processor 275provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover IP packets from the UE 250. IP packets from thecontroller/processor 275 may be provided to the core network 160. Thecontroller/processor 275 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

New radio (NR) may refer to radios configured to operate according to anew air interface (e.g., other than Orthogonal Frequency DivisionalMultiple Access (OFDMA)-based air interfaces) or fixed transport layer(e.g., other than Internet Protocol (IP)). NR may utilize OFDM with acyclic prefix (CP) on the uplink and downlink and may include supportfor half-duplex operation using time division duplexing (TDD). NR mayinclude Enhanced Mobile Broadband (eMBB) service targeting widebandwidth (e.g. 80 MHz beyond), millimeter wave (mmW) targeting highcarrier frequency (e.g. 60 GHz), massive MTC (mMTC) targetingnon-backward compatible MTC techniques, and/or mission criticaltargeting ultra-reliable low latency communications (URLLC) service.

A single component carrier bandwidth of 100 MHZ may be supported. In oneexample, NR resource blocks (RBs) may span 12 sub-carriers with asub-carrier bandwidth of 60 kHz over a 0.125 ms duration or a bandwidthof 15 kHz over a 0.5 ms duration. Each radio frame may consist of 20 or80 subframes (or NR slots) with a length of 10 ms. Each subframe mayindicate a link direction (i.e., DL or UL) for data transmission and thelink direction for each subframe may be dynamically switched. Eachsubframe may include DL/UL data as well as DL/UL control data. UL and DLsubframes for NR may be as described in more detail below with respectto FIGS. 5 and 6.

The NR RAN may include a central unit (CU) and distributed units (DUs).A NR BS (e.g., gNB, 5G Node B, Node B, transmission reception point(TRP), access point (AP)) may correspond to one or multiple BSs. NRcells can be configured as access cells (ACells) or data only cells(DCells). For example, the RAN (e.g., a central unit or distributedunit) can configure the cells. DCells may be cells used for carrieraggregation or dual connectivity and may not be used for initial access,cell selection/reselection, or handover. In some cases DCells may nottransmit synchronization signals (SS) in some cases DCells may transmitSS. NR BSs may transmit downlink signals to UEs indicating the celltype. Based on the cell type indication, the UE may communicate with theNR BS. For example, the UE may determine NR BSs to consider for cellselection, access, handover, and/or measurement based on the indicatedcell type.

FIG. 3 illustrates an example logical architecture 300 of a distributedRAN, according to aspects of the present disclosure. A 5G access node306 may include an access node controller (ANC) 302. The ANC may be acentral unit (CU) of the distributed RAN 300. The backhaul interface tothe next generation core network (NG-CN) 304 may terminate at the ANC.The backhaul interface to neighboring next generation access nodes(NG-ANs) may terminate at the ANC. The ANC may include one or more TRPs308 (which may also be referred to as BSs, NR BSs, Node Bs, 5G NBs, APs,or some other term). As described above, a TRP may be usedinterchangeably with “cell.”

The TRPs 308 may be a distributed unit (DU). The TRPs may be connectedto one ANC (ANC 302) or more than one ANC (not illustrated). Forexample, for RAN sharing, radio as a service (RaaS), and servicespecific AND deployments, the TRP may be connected to more than one ANC.A TRP may include one or more antenna ports. The TRPs may be configuredto individually (e.g., dynamic selection) or jointly (e.g., jointtransmission) serve traffic to a UE.

The local architecture of the distributed RAN 300 may be used toillustrate fronthaul definition. The architecture may be defined thatsupport fronthauling solutions across different deployment types. Forexample, the architecture may be based on transmit network capabilities(e.g., bandwidth, latency, and/or jitter). The architecture may sharefeatures and/or components with LTE. According to aspects, the nextgeneration AN (NG-AN) 310 may support dual connectivity with NR. TheNG-AN may share a common fronthaul for LTE and NR.

The architecture may enable cooperation between and among TRPs 308. Forexample, cooperation may be preset within a TRP and/or across TRPs viathe ANC 302. According to aspects, no inter-TRP interface may beneeded/present.

According to aspects, a dynamic configuration of split logical functionsmay be present within the architecture of the distributed RAN 300. ThePDCP, RLC, MAC protocol may be adaptably placed at the ANC or TRP.

FIG. 4 illustrates an example physical architecture of a distributed RAN400, according to aspects of the present disclosure. A centralized corenetwork unit (C-CU) 402 may host core network functions. The C-CU may becentrally deployed. C-CU functionality may be offloaded (e.g., toadvanced wireless services (AWS)), in an effort to handle peak capacity.A centralized RAN unit (C-RU) 404 may host one or more ANC functions.Optionally, the C-RU may host core network functions locally. The C-RUmay have distributed deployment. The C-RU may be closer to the networkedge. A distributed unit (DU) 406 may host one or more TRPs. The DU maybe located at edges of the network with radio frequency (RF)functionality.

FIG. 5 is a diagram 500 showing an example of a DL-centric subframe. TheDL-centric subframe may include a control portion 502. The controlportion 502 may exist in the initial or beginning portion of theDL-centric subframe. The control portion 502 may include variousscheduling information and/or control information corresponding tovarious portions of the DL-centric subframe. In some configurations, thecontrol portion 502 may be a physical DL control channel (PDCCH), asindicated in FIG. 5. The DL-centric subframe may also include a DL dataportion 504. The DL data portion 504 may sometimes be referred to as thepayload of the DL-centric subframe. The DL data portion 504 may includethe communication resources utilized to communicate DL data from thescheduling entity (e.g., UE or BS) to the subordinate entity (e.g., UE).In some configurations, the DL data portion 504 may be a physical DLshared channel (PDSCH).

The DL-centric subframe may also include a common UL portion 506. Thecommon UL portion 506 may sometimes be referred to as an UL burst, acommon UL burst, and/or various other suitable terms. The common ULportion 506 may include feedback information corresponding to variousother portions of the DL-centric subframe. For example, the common ULportion 506 may include feedback information corresponding to thecontrol portion 502. Non-limiting examples of feedback information mayinclude an ACK signal, a NACK signal, a HARQ indicator, and/or variousother suitable types of information. The common UL portion 506 mayinclude additional or alternative information, such as informationpertaining to random access channel (RACH) procedures, schedulingrequests (SRs), and various other suitable types of information.

As illustrated in FIG. 5, the end of the DL data portion 504 may beseparated in time from the beginning of the common UL portion 506. Thistime separation may sometimes be referred to as a gap, a guard period, aguard interval, and/or various other suitable terms. This separationprovides time for the switch-over from DL communication (e.g., receptionoperation by the subordinate entity (e.g., UE)) to UL communication(e.g., transmission by the subordinate entity (e.g., UE)). One ofordinary skill in the art will understand that the foregoing is merelyone example of a DL-centric subframe and alternative structures havingsimilar features may exist without necessarily deviating from theaspects described herein.

FIG. 6 is a diagram 600 showing an example of an UL-centric subframe.The UL-centric subframe may include a control portion 602. The controlportion 602 may exist in the initial or beginning portion of theUL-centric subframe. The control portion 602 in FIG. 6 may be similar tothe control portion 502 described above with reference to FIG. 5. TheUL-centric subframe may also include an UL data portion 604. The UL dataportion 604 may sometimes be referred to as the pay load of theUL-centric subframe. The UL portion may refer to the communicationresources utilized to communicate UL data from the subordinate entity(e.g., UE) to the scheduling entity (e.g., UE or BS). In someconfigurations, the control portion 602 may be a physical DL controlchannel (PDCCH).

As illustrated in FIG. 6, the end of the control portion 602 may beseparated in time from the beginning of the UL data portion 604. Thistime separation may sometimes be referred to as a gap, guard period,guard interval, and/or various other suitable terms. This separationprovides time for the switch-over from DL communication (e.g., receptionoperation by the scheduling entity) to UL communication (e.g.,transmission by the scheduling entity). The UL-centric subframe may alsoinclude a common UL portion 606. The common UL portion 606 in FIG. 6 maybe similar to the common UL portion 606 described above with referenceto FIG. 6. The common UL portion 606 may additionally or alternativelyinclude information pertaining to channel quality indicator (CQI),sounding reference signals (SRSs), and various other suitable types ofinformation. One of ordinary skill in the art will understand that theforegoing is merely one example of an UL-centric subframe andalternative structures having similar features may exist withoutnecessarily deviating from the aspects described herein.

In some circumstances, two or more subordinate entities (e.g., UEs) maycommunicate with each other using sidelink signals. Real-worldapplications of such sidelink communications may include public safety,proximity services, UE-to-network relaying, vehicle-to-vehicle (V2V)communications, Internet of Everything (IoE) communications, IoTcommunications, mission-critical mesh, and/or various other suitableapplications. Generally, a sidelink signal may refer to a signalcommunicated from one subordinate entity (e.g., UE1) to anothersubordinate entity (e.g., UE2) without relaying that communicationthrough the scheduling entity (e.g., UE or BS), even though thescheduling entity may be utilized for scheduling and/or controlpurposes. In some examples, the sidelink signals may be communicatedusing a licensed spectrum (unlike wireless local area networks, whichtypically use an unlicensed spectrum).

FIG. 7 is a diagram 700 illustrating communications between a basestation 702 and a UE 704. The base station 702 may send to the UE 704 anindication (e.g., via RRC signaling) indicating a particular time domainDMRS sequence 742. “DMRS” stands for Demodulation Reference Signal. Uponreceiving the indication, the UE 704 instructs a DMRS sequence component712 to generate the DMRS sequence 742. The DMRS sequence component 712accordingly generates the DMRS sequence 742. The DMRS sequence component712 sends the DMRS sequence 742 to the modulation component 714. Themodulation component 714 generates modulation symbols 744 representingthe DMRS sequence 742. The modulation component 714 then sends themodulation symbols 744 to a DFT-s-OFDM component 718. “DFT-s-OFDM”stands for Discrete Fourier Transmission-Single Carrier-OrthogonalFrequency Division Multiplexing.

More specifically, the DFT-s-OFDM component 718 includes a DFT component722, an optional FDSS component 724, a tone mapper 726, an IFFTcomponent 728, and a cyclic prefix component 730. “FDSS” stands forFrequency Domain Spectrum Shaping. “IFFT” stands for Inverse FastFourier Transform. The DFT component 722 performs a DFT on themodulation symbols 744. The outcome symbols from the DFT component 722may be optionally sent to the FDSS component 724. The outcome symbolsfrom the FDSS component 724 are then mapped to resource elements by thetone mapper 726. The resource elements carrying the symbols areconverted to a time domain signal by the IFFT component 728. The cyclicprefix component 730 further adds a cyclic prefix to the time domainsignal. As such, the UE 704 may transmit the DMRS sequence 742 to thebase station 702 through a Physical Uplink Control Channel (PUCCH) or aPhysical Uplink Shared Channel (PUSCH).

When the length of the DMRS sequence 742 is equal to or less than 24,the DMRS sequence 742 is selected from a set predeterminedcomputer-generate-sequences (CGSs). In particular, the set may contain30 base DMRS sequences. The set of predetermined CGSs may have desiredproperties such as good auto-correlation (within a delay window) orfrequency flatness, good cross-correlation (between any pair of 30 basesequences), and good Peak-to-Average Power Ratio (PAPR).

When the length of the DMRS sequence 742 is 12, 18, or 24, themodulation component 714 may employ a π2-BPSK modulation. When thelength of the DMRS sequence 742 is 6, the modulation component 714 mayemploy an 8-BPSK modulation.

Two different types of DMRSs can be configured, namely, DMRS Type 1 andType 2, which differ in the maximum number of orthogonal referencesignals and the mapping to the resource elements in the frequencydomain. Type 1 provides up to four orthogonal reference signals using asingle-symbol DMRS and up to eight orthogonal reference signals using adouble-symbol DMRS, whereas Type 2 provides 6 and 12 patterns for singleand double-symbol DMRS, respectively.

DMRS type 1 supports total four ports in an OFDM symbol. Two of portsmay share the same frequency domain locations (same code divisionmultiplexing (CDM) group). It, therefore, relies on properties of theDMRS sequences to achieve orthogonality (or low correlation) between theports. Table A below summaries UE multiplexing requirement for PUSCH,PUCCH format 3, and PUCCH format 4.

TABLE A PUCCH PUCCH PUSCH format 3 format 4 Sequence length 6, 12, 18,24, >=30 12, 24, >=36 12 # of UE mux 2 N/A 4 (in same CDM group)

In Release 15, the orthogonality is assured by time domain cyclic shiftsof a DMRS sequence that has constant amplitude in frequency domain.Furthermore, the shift values for each port are evenly distributed overthe base sequence length, so in time domain two ports are orthogonal notonly when they are fully aligned but also within a certain delay window.Note that the frequency pattern for the ports are [+, +, +, +,] and [+,−, +, −, +−, . . . ] respectively for each port.

Given a time domain π/2-BPSK base sequence, two possible schemes may beused to multiplex two ports (i.e., a 1st port and a 2nd port). In Scheme1, a time domain circular shift is applied to the 2nd port. For example,when the 1st port transmits the DMRS sequence 742, the 2nd porttransmits a DMRS sequence that is formed by applying a time domaincircular shift to the DMRS sequence 742. The DMRS sequence at the 2ndport can be formed by applying [+, −, +, −, +−, . . . ] in frequencydomain. With this approach, circular auto-correlation of the 2nd portmay be as good as the 1st port but zero correlation between two ports(within a delay window) may not be retained in general. However, due tothe property of Gold-sequence, the correlation can be still acceptable.

In Scheme 2: a time domain orthogonal mask can be applied to a base DMRSsequence at the 2nd port. Since pre-DFT time domain sequence hasconstant amplitude, we can apply a mask w=[w₀, w₁, . . . , w_(N−1)] (Nis base sequence length) such that

Σ_(i=0) ^(N−1) w _(i)=0.

This can generate two DMRS sequences that are orthogonal when the twoDMRS sequences are aligned. In order to maintain the same properties asπ2-BPSK, it is further restricted that w₁∈{1, −1} while the pattern of+1/−1 may be chosen. For example, w_(Blk)=[1, . . . , 1, −1, . . . , −1]may be considered as two equal sizes blocks of 1 and −1.

In another example, an interleaved pattern such as w_(intv)=[+1, −1, . .. , +1, −1] may be used. Applying w_(intv), is to circular shift (halfof the length) in the frequency domain waveform. In other words, the 2ndport can be prepared in either time or frequency domain. Both ways havesimpler implementations. When UE is in high speed environment, channelcould change rapidly in time. Alternative interleaved +1 and −1, asw_(intv), may maintain orthogonality between ports better.

In certain configurations, CGS-based sequences having a length of 12,18, or 24 bits are used for PUSCH with small RB allocations andCGS-based sequences having a length of 12 or 24 bits are also used inPUCCH format 3 and format 4.

In the case of PUSCH DMRS, two ports in the same CDM group are used.Both Scheme 1 and Scheme 2 can be considered as supporting two portsmultiplexing. 30 CGS sequences of length 18 or 24 are searched tosatisfy certain correlation properties, as described infra. One of thedifferences between two schemes is that Scheme 1 requires each basesequence itself has auto-correlation zeros for the window centered at 0and the window centered at N/2.

For PUCCH format 3, no multiple user multiplexing is required. For PUCCHformat 4, 4 users may need to be supported. Therefore, Scheme 1 andScheme 2 are combined to form a Scheme 3 to support 2 additional ports.

In Scheme 3, a time domain circular shift of 6 bits and pre-DFTorthogonal masks are applied to a base DMRS sequence of a length 12.S_(i) is a base DMRS sequence. w_(intv), =[w_(i)]i=0, . . . , 11. TheDMRS sequences at port 1, port 2, port 3, and port 4 are S_(i) ⁰, S_(i)¹, S_(i) ², S_(i) ³ as follows

s _(i) ⁰ =s _(i),

s _(i) ¹ =s _(i) ·w _(i),

s _(i) ² =s _(mod(i+6,12)),

s _(i) ³ =s _(mod(i+6,12)) ·w _(i).

As such, for length 12, multiple DMRS sequences can be generated byScheme 3 to support up to 4 UEs. For length 18 and length 24, two DMRSsequences may be generated by Scheme 1 and/or Scheme 2.

In certain configurations, for lengths supporting 2 ports (e.g., length18 or 24), DMRS sequences generated for port 0 and port 1 (generatedaccording to Scheme 1 or 2) both may have zero auto-correlation fordelays in window T_(A). It searches sequences that minimizes theauto-correlation in T_(B) (if T_(B) is not empty) and minimizescross-correlation in T_(A)∪T_(B)∪[0].

For the case supporting 4 ports (e.g., length 12), it is furtherrestricted that the cross-correlation between any pair of the 4 portsare zero at delay=0. 30 such sequence may be identified as having goodcross-correlation property in T_(A)∪T_(B)∪[0].

Table B below shows base sequences of length 12 generated based onScheme 3.

TABLE B Index sequence PAPR 0 0 0 0 0 0 1 1 0 1 1 0 1 1.1896, 0.7793,0.7794, 1.1900 1 0 0 0 0 1 1 0 1 1 0 1 0 1.2957, 1.7260, 1.7260, 1.29572 0 0 0 1 0 0 1 0 0 0 1 0 1.1900, 0.7794, 0.7793, 1.1896 3 0 0 1 0 1 1 10 1 1 1 0 1.2955, 1.7260, 1.7262, 1.2957 4 0 0 1 1 1 0 0 1 0 1 0 01.7260, 1.1900, 1.2957, 0.7793 5 0 0 1 1 1 1 1 0 1 0 0 1 1.1896, 0.7793,0.7794, 1.1900 6 0 1 0 0 0 1 0 0 1 0 0 0 1.1896, 0.7794, 0.7794, 1.18967 0 1 0 0 0 1 1 1 0 1 0 0 1.1896, 0.7787, 0.7787, 1.1896 8 0 1 0 0 0 1 11 0 1 1 1 1.2957, 1.7262, 1.7260, 1.2955 9 0 1 0 1 1 0 0 0 1 1 1 11.2948, 1.7260, 1.7254, 1.2957 10 0 1 1 0 0 0 1 1 1 1 0 1 1.7260,0.7787, 1.2957, 1.1896 11 0 1 1 0 1 0 0 0 0 0 1 1 1.2948, 1.7260,1.7254, 1.2957 12 0 1 1 0 1 0 1 1 1 1 0 0 1.2948, 1.1896, 1.7254, 0.778713 0 1 1 1 0 0 1 0 1 0 0 0 1.7260, 1.7260, 1.2957, 1.2957 14 0 1 1 1 1 10 1 0 0 1 0 1.7254, 1.2948, 1.2948, 1.7254 15 1 0 0 0 0 0 1 1 0 1 1 01.1896, 0.7793, 0.7794, 1.1900 16 1 0 0 0 1 0 0 0 1 1 1 0 1.2957,1.7260, 1.7260, 1.2957 17 1 0 0 0 1 0 1 1 1 0 0 0 1.1900, 0.7794,0.7793, 1.1896 18 1 0 0 0 1 1 1 0 1 1 1 0 1.2955, 1.7260, 1.7262, 1.295719 1 0 0 1 0 0 0 0 1 0 0 0 1.7260, 1.1900, 1.2957, 0.7793 20 1 0 0 1 0 00 1 0 0 0 0 1.1896, 0.7793, 0.7794, 1.1900 21 1 0 1 1 0 0 0 0 0 1 0 11.1896, 0.7794, 0.7794, 1.1896 22 1 0 1 1 0 1 1 1 1 0 1 1 1.1896,0.7787, 0.7787, 1.1896 23 1 0 1 1 1 0 0 0 1 0 1 1 1.2957, 1.7262,1.7260, 1.2955 24 1 0 1 1 1 0 1 0 0 0 1 1 1.2948, 1.7260, 1.7254, 1.295725 1 0 1 1 1 1 0 0 0 1 1 0 1.7260, 0.7787, 1.2957, 1.1896 26 1 0 1 1 1 10 1 1 0 1 1 1.2948, 1.7260, 1.7254, 1.2957 27 1 1 0 1 0 0 0 1 0 0 0 11.2948, 1.1896, 1.7254, 0.7787 28 1 1 0 1 1 0 1 1 1 0 1 1 1.7260,1.7260, 1.2957, 1.2957 29 1 1 0 1 1 1 0 1 1 1 1 0 1.7254, 1.2948,1.2948, 1.7254

Table C below shows base sequences of length 18 generated based onScheme 1.

TABLE C Index sequence PAPR 0 0 0 0 0 1 0 1 0 0 0 0 0 1 1 0 1 1 01.3798, 1.0231 1 0 0 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 0 0.9637, 1.3795 2 00 0 0 1 1 1 0 1 0 1 0 1 0 0 1 1 1 0.9646, 0.9907 3 0 0 0 1 0 1 0 0 1 1 10 0 1 0 1 0 0 1.0239, 1.1808 4 0 0 0 1 0 1 0 1 0 1 1 0 0 0 1 1 1 11.0213, 1.0231 5 0 0 0 1 1 0 0 0 1 1 0 1 0 1 0 1 1 1 1.3056, 1.2438 6 00 0 1 1 1 0 0 0 1 0 0 0 1 1 1 1 1 1.3972, 0.9916 7 0 0 0 1 1 1 1 0 1 1 10 1 1 1 1 0 0 1.3808, 1.2444 8 0 0 0 1 1 1 1 1 0 0 0 1 1 1 0 0 0 10.9655, 1.1496 9 0 0 1 0 0 0 1 0 0 1 0 1 0 0 1 0 0 1 0.9655, 1.3977 10 00 1 0 0 0 1 1 1 1 1 0 0 0 1 0 0 0 1.3069, 1.0581 11 0 0 1 0 0 1 0 0 0 00 0 0 1 1 0 1 1 0.9909, 1.1499 12 0 0 1 0 1 0 0 0 1 0 1 0 0 1 0 0 0 11.2443, 1.3987 13 0 0 1 1 0 1 0 1 0 1 1 1 0 0 0 1 1 0 1.3985, 1.1795 140 0 1 1 0 1 1 0 0 0 0 0 1 0 1 0 0 0 1.1450, 1.3970 15 0 1 0 0 0 0 0 0 01 1 0 1 1 0 0 1 0 1.3798, 1.0231 16 0 1 0 1 0 1 1 0 0 0 1 1 1 1 0 0 0 10.9637, 1.3795 17 0 1 1 0 0 0 0 0 0 0 1 1 0 1 0 0 0 1 0.9646, 0.9907 180 1 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1.0239, 1.1808 19 0 1 1 1 0 1 0 0 11 1 0 0 1 0 1 1 1 1.0213, 1.0231 20 0 1 1 1 1 1 0 1 1 1 0 0 0 0 0 1 1 11.3056, 1.2438 21 1 0 0 1 0 0 0 1 1 1 0 0 0 1 0 0 1 0 1.3972, 0.9916 221 0 1 0 1 0 0 0 1 1 1 0 0 1 1 1 0 0 1.3808, 1.2444 23 1 0 1 0 1 1 0 0 00 1 0 0 0 0 1 1 0 0.9655, 1.1496 24 1 0 1 1 0 0 1 0 0 1 0 0 0 0 0 0 0 10.9655, 1.3977 25 1 0 1 1 1 0 1 1 0 1 0 1 1 1 0 1 0 1 1.3069, 1.0581 261 0 1 1 1 1 1 0 0 0 1 0 0 0 1 1 1 1 0.9909, 1.1499 27 1 1 0 0 0 0 0 1 11 1 0 1 1 1 0 1 1 1.2443, 1.3987 28 1 1 1 0 0 0 0 1 1 1 0 0 1 0 1 0 1 01.3985, 1.1795 29 1 1 1 0 1 1 1 0 1 1 1 1 0 0 1 0 0 1 1.1450, 1.3970

Table D below shows base sequences of length 24 generated based onScheme 1.

TABLE D Index sequence PAPR 0 0 0 0 0 0 0 1 1 1 0 0 0 1 1 1 0 0 0 1 0 00 0 1 1.5926, 1.5926 1 0 0 0 0 1 0 0 0 0 1 0 0 0 1 1 1 0 0 0 1 1 1 0 01.1500, 1.4099 2 0 0 0 0 1 0 0 0 0 1 1 0 0 0 1 1 1 0 1 0 1 0 1 1 1.6543,1.6499 3 0 0 1 0 0 1 0 0 1 1 0 1 0 0 0 1 0 1 1 0 0 0 0 0 1.1476, 1.65424 0 0 1 0 0 1 0 0 1 0 0 1 0 1 0 1 1 1 0 1 0 0 0 1 1.6543, 1.4091 5 0 0 10 0 0 1 1 1 0 0 0 1 1 1 0 0 0 0 0 0 1 0 0 1.5912, 1.1500 6 0 0 1 0 1 1 00 0 0 0 0 0 1 0 0 1 0 0 1 1 0 1 0 1.6542, 1.4099 7 0 0 1 1 1 0 0 0 1 1 10 0 0 0 0 0 1 0 0 0 0 1 0 1.5926, 1.1476 8 0 0 1 0 1 1 1 0 1 0 1 0 0 1 00 1 0 0 1 0 0 1 0 1.5926, 1.1500 9 1 0 0 1 0 0 0 0 0 0 0 1 1 0 1 0 0 0 10 1 1 0 0 1.6543, 1.5926 10 1 0 0 0 0 1 0 0 0 1 1 1 0 0 0 1 1 1 0 0 0 00 0 1.4106, 1.4091 11 1 0 0 0 0 0 0 0 1 1 0 1 0 0 0 1 0 1 1 0 0 1 0 01.6543, 1.5926 12 1 0 0 1 0 1 0 1 1 1 0 1 0 0 0 1 0 0 1 0 0 1 0 01.1476, 1.5918 13 1 0 0 0 0 0 0 0 1 0 0 1 0 0 1 1 0 1 0 0 0 1 0 11.5912, 1.6543 14 1 0 0 0 1 1 1 0 0 0 1 1 1 1 1 1 0 1 1 1 1 0 1 11.1476, 1.6543 15 1 1 0 0 1 0 1 0 1 0 0 0 1 1 1 0 0 1 1 1 1 0 1 11.5926, 1.5926 16 1 0 0 0 1 1 1 1 1 1 0 1 1 1 1 0 1 1 1 0 0 0 1 11.1500, 1.4099 17 1 1 0 0 1 0 1 1 1 0 1 0 0 1 1 0 1 1 0 1 1 1 1 11.6543, 1.6499 18 1 0 1 1 0 1 1 1 0 1 0 0 0 1 0 1 0 1 1 0 1 1 0 11.1476, 1.6542 19 1 1 1 0 0 0 1 0 0 0 0 1 0 0 0 0 0 0 1 1 1 0 0 01.6543, 1.4091 20 1 1 1 0 0 0 1 1 0 0 0 0 1 0 0 0 0 1 1 0 1 0 1 01.5912, 1.1500 21 1 0 1 0 0 0 1 0 1 1 0 0 1 0 0 1 0 0 0 0 0 0 0 11.6542, 1.4099 22 1 0 1 1 0 1 1 0 1 1 0 1 1 1 0 1 0 0 0 1 0 1 0 11.5926, 1.1476 23 1 1 1 0 0 0 1 1 1 0 0 0 1 0 0 0 0 1 0 0 0 0 0 01.5926, 1.1500 24 1 0 1 0 0 0 1 1 1 0 0 1 1 1 1 0 1 1 1 1 0 0 1 01.6543, 1.5926 25 1 0 1 0 0 0 1 0 1 0 1 1 0 1 1 0 1 1 0 1 1 0 1 11.4106, 1.4091 26 1 1 1 0 0 0 1 1 1 1 1 1 0 1 1 1 1 0 1 1 1 0 0 01.6543, 1.5926 27 1 0 1 0 0 0 1 0 1 1 1 0 1 1 0 1 1 0 1 1 0 1 1 01.1476, 1.5918 28 1 1 1 0 0 1 1 1 1 0 1 1 1 1 0 0 1 0 1 0 1 0 0 01.5912, 1.6543 29 1 0 1 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 1 11.1476, 1.6543

Table E below shows base sequences of length 24 generated based onScheme 2.

TABLE E Index sequence PAPR 0 0 0 0 0 0 0 1 0 0 1 0 0 1 1 1 0 1 0 1 0 01 1 1 1.0125, 1.0233 1 0 0 0 0 0 0 1 1 0 0 1 0 1 0 0 1 1 0 1 0 1 1 1 01.2587, 1.5191 2 0 0 0 0 1 0 0 1 0 1 0 1 0 0 1 1 0 0 0 0 0 1 1 0 1.2582,1.5141 3 0 0 0 0 1 0 0 0 0 1 1 0 1 1 1 0 1 0 0 0 1 1 0 1 1.1758, 1.25814 0 0 0 0 1 0 0 1 0 0 1 1 1 0 1 0 1 0 0 1 1 1 0 0 1.0129, 1.0244 5 0 0 00 1 0 0 1 1 0 1 0 0 0 0 0 1 1 0 0 0 1 0 1 1.7849, 1.5275 6 0 0 0 0 1 1 00 1 0 1 0 0 1 1 0 1 0 1 1 1 0 0 0 1.2582, 1.5141 7 0 0 0 0 1 0 0 1 1 1 11 1 0 0 1 0 1 0 1 0 0 1 1 1.0238, 1.1638 8 0 0 0 0 1 1 0 0 1 0 1 1 1 0 01 0 1 0 1 1 0 0 0 1.0243, 1.1660 9 0 0 0 0 1 1 0 0 1 0 1 0 1 0 0 1 1 1 11 1 0 0 1 1.0238, 1.1638 10 0 0 0 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 1 0 1 11 0 1.3149, 1.5081 11 0 0 0 0 1 0 1 1 0 0 0 1 0 1 1 1 0 1 1 0 0 0 0 11.1758, 1.2581 12 0 0 0 0 1 1 1 0 0 1 0 1 0 1 1 1 0 0 1 0 0 1 0 01.0125, 1.0233 13 0 0 0 0 1 0 1 1 0 0 1 0 0 0 0 1 0 1 0 0 0 1 1 01.5288, 1.7809 14 0 0 0 0 1 1 1 0 0 0 1 0 0 1 0 1 0 0 0 1 0 0 1 01.3112, 1.5049 15 0 0 0 0 1 0 1 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 11.7849, 1.5275 16 0 0 0 0 1 1 1 0 1 1 0 1 1 0 1 0 1 1 1 0 0 0 1 01.5049, 1.3112 17 0 0 0 0 1 0 1 1 1 0 1 0 0 1 1 1 0 1 1 1 1 0 1 11.1758, 1.2581 18 0 0 0 0 1 1 1 0 1 0 1 1 0 0 1 0 1 0 0 1 1 0 0 01.5141, 1.2582 19 0 0 1 0 0 0 0 1 0 1 0 0 0 1 1 0 0 0 0 0 1 0 1 11.5275, 1.7849 20 0 0 1 0 0 1 0 1 0 0 0 1 0 0 1 0 0 0 0 0 1 1 1 01.3137, 1.5059 21 0 0 1 0 0 1 0 0 0 1 0 1 0 0 1 0 0 0 1 1 1 0 0 01.5049, 1.3112 22 0 0 1 0 0 1 0 1 0 1 0 0 1 1 0 0 0 0 0 1 1 0 0 01.2590, 1.5194 23 0 0 1 0 0 1 0 0 0 0 0 1 1 1 0 0 0 1 0 0 1 0 1 01.5059, 1.3137 24 0 0 1 0 0 1 0 1 0 0 0 1 1 1 0 1 1 1 1 1 0 0 0 11.5081, 1.3149 25 0 0 1 0 0 1 0 0 0 0 0 0 1 1 1 0 0 1 0 1 0 1 1 11.0129. 1.0244 26 0 0 1 0 0 1 0 1 0 1 1 1 0 0 0 1 1 0 1 1 1 1 1 11.0244, 1.0129 27 0 0 1 0 0 0 0 1 0 1 1 0 0 0 1 0 1 1 1 0 1 1 0 01.2581, 1.1758 28 0 0 1 0 0 0 0 0 0 1 1 0 1 1 0 1 0 1 0 0 0 1 1 11.0129, 1.0244 29 0 0 1 0 0 1 0 0 0 1 1 1 1 1 0 1 1 1 0 0 0 1 0 11.3112, 1.5049

Due to a short length, binary sequence with length 6 may not provide 30candidates with desired properties. In certain configurations, asdescribed supra, for DMRS sequence of length 6, the modulation component714 employs an 8-BPSK modulation. In certain configurations, based onthe indication from the base station 702, the modulation component 714generates modulation symbols 744. The modulation symbols 744 may berepresented as

s _(u)(n)=e ^(jϕ(n)π/8)

The values of ϕ(n) in each base sequence are listed in the below Table Fand Table G.

TABLE F u ϕ(0), . . . , ϕ(5) PAPR (dB)  0 1 3 1 7 −3 −7 2.0214  1 1 3 1−5 5 −7 1.9297  2 1 3 −3 7 5 −7 1.9507  3 1 5 3 −3 7 −7 1.9507  4 1 5 −1−7 7 −7 1.9298  5 1 −3 1 −3 1 −3 1.8257  6 1 −3 3 −7 7 −7 2.0214  7* 1−3 −7 −3 1 5 0.7838  8* 1 −3 −7 −3 1 −3 1.5331  9* 1 −3 −7 −3 −7 −31.5333 10 1 −1 1 5 −5 7 1.9143 11 1 −1 1 −5 7 −3 1.9943 12 1 −1 3 7 1 51.6125 13 1 −1 3 7 1 −3 1.8358  14* 1 −1 3 7 3 7 1.4624 15 1 −1 3 7 3 −31.4418 16 1 −1 3 7 −5 7 1.9852 17 1 −1 3 −7 5 −1 1.9942 18 1 −1 3 −3 1 51.7817 19 1 −1 3 −3 1 −3 1.7821 20 1 −1 3 −3 −7 −3 1.4418 21 1 −1 3 −1 37 1.6341 22 1 −1 3 −1 3 −3 1.7821 23 1 −1 3 −1 −7 −3 1.8359 24 1 −1 −7 5−7 −3 1.9853 25 1 −1 −7 5 −5 −1 1.9144 26 1 −1 −7 −3 1 −3 1.6341  27* 1−1 −7 −3 −7 −3 1.4624 28 1 −1 −5 −1 3 −3 1.7817 29 1 −1 −5 −1 −7 −31.6126

TABLE G u ϕ(0), . . . , ϕ(5) PAPR (dB)  0 1 3 8 3 −2 −4 1.9053  1 1 3 83 −1 −4 1.9468  2 1 4 1 5 0 −4 1.8828  3* 1 4 8 −3 −6 5 1.3821  4 1 4 −74 1 −3 1.9658  5 1 5 0 4 0 −3 1.5759  6 1 5 1 5 −7 5 1.5331  7 1 5 3 6 1−4 1.5936  8 1 5 8 4 −1 −4 1.3821  9* 1 5 −7 6 2 6 1.5758 10 1 5 −6 5 14 1.7337 11 1 5 −6 6 1 −2 1.4665 12 1 5 −6 6 2 5 1.8650 13 1 5 −6 8 3 −21.3993 14 1 6 8 3 −1 −4 1.7834 15 1 6 −7 5 1 −3 1.9500 16 1 6 −7 7 2 −31.7900 17 1 6 −6 6 2 −2 1.9503  18* 1 6 −6 6 −7 6 1.9287 19 1 −4 7 −6 8−4 1.5937 20 1 −4 8 5 −7 −4 1.9744  21* 1 −4 −7 −4 8 −4 1.9287 22 1 −4−6 5 8 −4 1.9375  23* 1 −3 8 5 −6 −2 1.3821 24 1 −3 −7 5 −7 −3 0.7839 251 −3 −6 5 −6 −3 1.9658 26 1 −2 −7 5 −6 −1 1.9045 27 1 −1 −6 5 7 −41.5718 28 1 −1 −6 5 −7 −4 1.5310 29 1 −1 −6 5 −6 −3 1.9541

Sequences marked with * are a subset with better auto-/cross-correlationand PAPR.

The sequences in Table F and Table G are normalized to have samestarting phase (i.e., e{circumflex over ( )}(jπ/8)). Because PAPR,circular auto-correlation and cross-correlation properties are invariantwith respect to constant phase rotation or circular shift, the actualsequences can be derived by applying such operations to the sequences inTable F and Table G.

In particular, the DMRS sequences listed in the below Table H can bederived from a sequence listed in Table F or Table G.

TABLE H u ϕ(0) . . . ϕ(5) 0 −1 −7 −3 −5 −1 3 1 −1 3 1 5 −1 −5 2 −7 −3 −75 −7 −3 3 −7 −3 −7 −3 7 −5 4 −7 −3 1 −5 −1 −5 5 −3 7 −5 −1 −5 −1 6 5 −77 1 5 1 7 1 5 1 5 3 7 8 1 −3 1 −5 −1 3

Further, in Scheme 4, when the length of a desired base DMRS sequence isN (e.g., 24), to generate a DMRS sequence for port 2, the DMRS sequencecomponent 712 initially generates a base DMRS sequence having a lengthof N/2 (e.g., 12). The DMRS sequence of length N/2 is sent to themodulation component 714 to generate a set of symbols (e.g., N/2). Theset of symbols is repeated to generate a duplicate set of symbols (e.g.,total N symbols). The below time domain orthogonal cover code (TD-OCC)is applied to the symbols.

$\left\lbrack {W_{N/2},{- W_{N/2}}} \right\rbrack,{{{where}\mspace{14mu} {W_{N/2}(n)}} = \left( {- 1} \right)^{n}},{n = 0},\ldots \;,{\frac{N}{2} - {1.}}$

For example, the TD-OCC may be [1, −1. 1, −1. 1, −1. 1, −1. 1, −1. 1,−1. −1. 1, −1, 1, −1. 1, −1. 1, −1. 1, −1. 1]. Subsequently, the symbolsapplied with TD-OCC are sent to the DFT-s-OFDM component 718.

In Scheme 5, to generate a DMRS sequence of length N for port 2, theDMRS sequence component 712 initially generates a base DMRS sequence ofN (e.g., 12). The DMRS sequence of length N is sent to the modulationcomponent 714 to generate a set of symbols (e.g., N). The below TD-OCCis applied to the symbols.

$\left\lbrack {e^{j\frac{2\pi n}{N}} \cdot {W_{N}(n)}} \right\rbrack_{{n = 0},\; \ldots \;,\; {N - 1}},{{{where}\mspace{14mu} {W_{N}(n)}} = \left( {- 1} \right)^{n}},{n = 0},\ldots \;,{N - 1.}$

FIG. 8 is a flow chart 800 of a method (process) for generating andtransmitting a DMRS sequence. The method may be performed by a first UE(e.g., the UE 704, the apparatus 902, and the apparatus 902′).

At operation 802, the UE receives an indication for transmitting aparticular DMRS sequence in an uplink transmission. The particular DMRSsequence is time domain based. At operation 804, the UE determines anadjustment to a base DMRS sequence for generating the particular DMRSsequence. At operation 806, the UE generates the particular DMRSsequence based on the adjustment and the base DMRS sequence. Atoperation 808, the UE modulates the particular DMRS sequence to obtain aset of symbols. At operation 810, the UE maps a plurality of symbols ofthe set of symbols to a plurality of subcarriers. At operation 812, theUE transmits the plurality of symbols on the plurality of subcarriers.

In certain configurations, the adjustment is an orthogonal mask. Theparticular DMRS sequence is generated by applying the orthogonal mask tothe base DMRS sequence. A length of the base DMRS sequence may be N. Theorthogonal mask is w=[w₀, w₁, . . . , w_(n−1)] and satisfies the belowcondition:

Σ_(i=0) ^(N−1) w _(i)=0

The adjustment may further include a time domain circular shift. Theparticular DMRS sequence is generated by further applying the timedomain circular shift to the base DMRS sequence applied with theorthogonal mask.

In certain configurations, the adjustment is a time domain circularshift. The particular DMRS sequence is generated by applying the timedomain circular shift to the base DMRS sequence. The adjustment mayfurther include an orthogonal mask. The particular DMRS sequence isgenerated by further applying the orthogonal mask to the base DMRSsequence applied with the time domain circular shift.

In certain configurations, a length the base DMRS sequence is half of alength of the particular DMRS sequence. The adjustment is a time domainrepetition and an orthogonal mask. The particular DMRS sequence isgenerated by repeating the base DMRS sequence and applying theorthogonal mask to the repeated base DMRS sequence.

FIG. 9 is a conceptual data flow diagram 900 illustrating the data flowbetween different components/means in an exemplary apparatus 902. Theapparatus 902 may be a UE. The apparatus 902 includes a receptioncomponent 904, a DMRS sequence generator 906, a modulation component908, an OFDM component 909, and a transmission component 910.

The DMRS sequence generator 906 receives an indication from a basestation 950 for transmitting a particular DMRS sequence in an uplinktransmission. The particular DMRS sequence is time domain based. TheDMRS sequence generator 906 determines an adjustment to a base DMRSsequence for generating the particular DMRS sequence. The DMRS sequencegenerator 906 generates the particular DMRS sequence based on theadjustment and the base DMRS sequence. The modulation component 908modulates the particular DMRS sequence to obtain a set of symbols. TheOFDM component 909 maps a plurality of symbols of the set of symbols toa plurality of subcarriers. The transmission component 910 transmits theplurality of symbols on the plurality of subcarriers.

In certain configurations, the adjustment is an orthogonal mask. Theparticular DMRS sequence is generated by applying the orthogonal mask tothe base DMRS sequence. A length of the base DMRS sequence may be N. Theorthogonal mask is w=[w₀, w₁, . . . , w_(n−1)] and satisfies the belowcondition:

Σw _(i=0) ^(N−1) w ^(i)=0.

The adjustment may further include a time domain circular shift. Theparticular DMRS sequence is generated by further applying the timedomain circular shift to the base DMRS sequence applied with theorthogonal mask.

In certain configurations, the adjustment is a time domain circularshift. The particular DMRS sequence is generated by applying the timedomain circular shift to the base DMRS sequence. The adjustment mayfurther include an orthogonal mask. The particular DMRS sequence isgenerated by further applying the orthogonal mask to the base DMRSsequence applied with the time domain circular shift.

In certain configurations, a length the base DMRS sequence is half of alength of the particular DMRS sequence. The adjustment is a time domainrepetition and an orthogonal mask. The particular DMRS sequence isgenerated by repeating the base DMRS sequence and applying theorthogonal mask to the repeated base DMRS sequence.

FIG. 10 is a diagram 1000 illustrating an example of a hardwareimplementation for an apparatus 902′ employing a processing system 1014.The apparatus 902′ may be a UE. The processing system 1014 may beimplemented with a bus architecture, represented generally by a bus1024. The bus 1024 may include any number of interconnecting buses andbridges depending on the specific application of the processing system1014 and the overall design constraints. The bus 1024 links togethervarious circuits including one or more processors and/or hardwarecomponents, represented by one or more processors 1004, the receptioncomponent 904, the DMRS sequence generator 906, the modulation component908, the OFDM component 909, the transmission component 910, and acomputer-readable medium/memory 1006. The bus 1024 may also link variousother circuits such as timing sources, peripherals, voltage regulators,and power management circuits, etc.

The processing system 1014 may be coupled to a transceiver 1010, whichmay be one or more of the transceivers 354. The transceiver 1010 iscoupled to one or more antennas 1020, which may be the communicationantennas 352.

The transceiver 1010 provides a means for communicating with variousother apparatus over a transmission medium. The transceiver 1010receives a signal from the one or more antennas 1020, extractsinformation from the received signal, and provides the extractedinformation to the processing system 1014, specifically the receptioncomponent 904. In addition, the transceiver 1010 receives informationfrom the processing system 1014, specifically the transmission component910, and based on the received information, generates a signal to beapplied to the one or more antennas 1020.

The processing system 1014 includes one or more processors 1004 coupledto a computer-readable medium/memory 1006. The one or more processors1004 are responsible for general processing, including the execution ofsoftware stored on the computer-readable medium/memory 1006. Thesoftware, when executed by the one or more processors 1004, causes theprocessing system 1014 to perform the various functions described suprafor any particular apparatus. The computer-readable medium/memory 1006may also be used for storing data that is manipulated by the one or moreprocessors 1004 when executing software. The processing system 1014further includes at least one of the reception component 904, the DMRSsequence generator 906, the modulation component 908, the OFDM component909, and the transmission component 910. The components may be softwarecomponents running in the one or more processors 1004, resident/storedin the computer readable medium/memory 1006, one or more hardwarecomponents coupled to the one or more processors 1004, or somecombination thereof. The processing system 1014 may be a component ofthe UE 350 and may include the memory 360 and/or at least one of the TXprocessor 368, the RX processor 356, and the communication processor359.

In one configuration, the apparatus 902/apparatus 902′ for wirelesscommunication includes means for performing each of the operations ofFIG. 8. The aforementioned means may be one or more of theaforementioned components of the apparatus 902 and/or the processingsystem 1014 of the apparatus 902′ configured to perform the functionsrecited by the aforementioned means.

As described supra, the processing system 1014 may include the TXProcessor 368, the RX Processor 356, and the communication processor359. As such, in one configuration, the aforementioned means may be theTX Processor 368, the RX Processor 356, and the communication processor359 configured to perform the functions recited by the aforementionedmeans.

It is understood that the specific order or hierarchy of blocks in theprocesses/flowcharts disclosed is an illustration of exemplaryapproaches. Based upon design preferences, it is understood that thespecific order or hierarchy of blocks in the processes/flowcharts may berearranged. Further, some blocks may be combined or omitted. Theaccompanying method claims present elements of the various blocks in asample order, and are not meant to be limited to the specific order orhierarchy presented.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” The word “exemplary” is used hereinto mean “serving as an example, instance, or illustration.” Any aspectdescribed herein as “exemplary” is not necessarily to be construed aspreferred or advantageous over other aspects. Unless specifically statedotherwise, the term “some” refers to one or more. Combinations such as“at least one of A, B, or C,” “one or more of A, B, or C,” “at least oneof A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or anycombination thereof” include any combination of A, B, and/or C, and mayinclude multiples of A, multiples of B, or multiples of C. Specifically,combinations such as “at least one of A, B, or C,” “one or more of A, B,or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and“A, B, C, or any combination thereof” may be A only, B only, C only, Aand B, A and C, B and C, or A and B and C, where any such combinationsmay contain one or more member or members of A, B, or C. All structuraland functional equivalents to the elements of the various aspectsdescribed throughout this disclosure that are known or later come to beknown to those of ordinary skill in the art are expressly incorporatedherein by reference and are intended to be encompassed by the claims.Moreover, nothing disclosed herein is intended to be dedicated to thepublic regardless of whether such disclosure is explicitly recited inthe claims. The words “module,” “mechanism,” “element,” “device,” andthe like may not be a substitute for the word “means.” As such, no claimelement is to be construed as a means plus function unless the elementis expressly recited using the phrase “means for.”

What is claimed is:
 1. A method of wireless communication of a userequipment (UE), comprising: receiving an indication for transmitting aparticular demodulation reference signal (DMRS) sequence in an uplinktransmission, the particular DMRS sequence being time domain based;determining an adjustment to a base DMRS sequence for generating theparticular DMRS sequence; generating the particular DMRS sequence basedon the adjustment and the base DMRS sequence; modulating the particularDMRS sequence to obtain a set of symbols; mapping a plurality of symbolsof the set of symbols to a plurality of subcarriers; and transmittingthe plurality of symbols on the plurality of subcarriers.
 2. The methodof claim 1, wherein the adjustment is an orthogonal mask, wherein theparticular DMRS sequence is generated by applying the orthogonal mask tothe base DMRS sequence.
 3. The method of claim 2, wherein a length ofthe base DMRS sequence is N, wherein the orthogonal mask is w=[w₀, w₁, .. . , w_(n−1)] and satisfies the below condition:Σ_(i=0) ^(N−1) w _(i)=0.
 4. The method of claim 2, wherein theadjustment further includes a time domain circular shift, wherein theparticular DMRS sequence is generated by further applying the timedomain circular shift to the base DMRS sequence applied with theorthogonal mask.
 5. The method of claim 1, wherein the adjustment is atime domain circular shift, wherein the particular DMRS sequence isgenerated by applying the time domain circular shift to the base DMRSsequence.
 6. The method of claim 5, wherein the adjustment furtherincludes an orthogonal mask, wherein the particular DMRS sequence isgenerated by further applying the orthogonal mask to the base DMRSsequence applied with the time domain circular shift.
 7. The method ofclaim 1, wherein a length the base DMRS sequence is half of a length ofthe particular DMRS sequence, wherein the adjustment is an time domainrepetition and an orthogonal mask, wherein the particular DMRS sequenceis generated by repeating the base DMRS sequence and applying theorthogonal mask to the repeated base DMRS sequence.
 8. An apparatus forwireless communication, the apparatus being a user equipment (UE),comprising: a memory; and at least one processor coupled to the memoryand configured to: receive an indication for transmitting a particulardemodulation reference signal (DMRS) sequence in an uplink transmission,the particular DMRS sequence being time domain based; determine anadjustment to a base DMRS sequence for generating the particular DMRSsequence; generate the particular DMRS sequence based on the adjustmentand the base DMRS sequence; modulate the particular DMRS sequence toobtain a set of symbols; map a plurality of symbols of the set ofsymbols to a plurality of subcarriers; and transmit the plurality ofsymbols on the plurality of subcarriers.
 9. The apparatus of claim 8,wherein the adjustment is an orthogonal mask, wherein the particularDMRS sequence is generated by applying the orthogonal mask to the baseDMRS sequence.
 10. The apparatus of claim 9, wherein a length of thebase DMRS sequence is N, wherein the orthogonal mask is w=[w₀, w₁, . . ., w_(n−1)] and satisfies the below condition:Σw _(i=0) ^(N−1) w _(i)=0.
 11. The apparatus of claim 9, wherein theadjustment further includes a time domain circular shift, wherein theparticular DMRS sequence is generated by further applying the timedomain circular shift to the base DMRS sequence applied with theorthogonal mask.
 12. The apparatus of claim 8, wherein the adjustment isa time domain circular shift, wherein the particular DMRS sequence isgenerated by applying the time domain circular shift to the base DMRSsequence.
 13. The apparatus of claim 12, wherein the adjustment furtherincludes an orthogonal mask, wherein the particular DMRS sequence isgenerated by further applying the orthogonal mask to the base DMRSsequence applied with the time domain circular shift.
 14. The apparatusof claim 8, wherein a length the base DMRS sequence is half of a lengthof the particular DMRS sequence, wherein the adjustment is an timedomain repetition and an orthogonal mask, wherein the particular DMRSsequence is generated by repeating the base DMRS sequence and applyingthe orthogonal mask to the repeated base DMRS sequence.
 15. Acomputer-readable medium storing computer executable code for wirelesscommunication of a user equipment (UE), comprising code to: receive anindication for transmitting a particular demodulation reference signal(DMRS) sequence in an uplink transmission, the particular DMRS sequencebeing time domain based; determine an adjustment to a base DMRS sequencefor generating the particular DMRS sequence; generate the particularDMRS sequence based on the adjustment and the base DMRS sequence;modulate the particular DMRS sequence to obtain a set of symbols; map aplurality of symbols of the set of symbols to a plurality ofsubcarriers; and transmit the plurality of symbols on the plurality ofsubcarriers.
 16. The computer-readable medium of claim 15, wherein theadjustment is an orthogonal mask, wherein the particular DMRS sequenceis generated by applying the orthogonal mask to the base DMRS sequence.17. The computer-readable medium of claim 16, wherein a length of thebase DMRS sequence is N, wherein the orthogonal mask is w=[w₀, w₁, . . ., w_(n−1)] and satisfies the below condition:Σ_(i=0) ^(N−1) w _(i)=0.
 18. The computer-readable medium of claim 16,wherein the adjustment further includes a time domain circular shift,wherein the particular DMRS sequence is generated by further applyingthe time domain circular shift to the base DMRS sequence applied withthe orthogonal mask.
 19. The computer-readable medium of claim 15,wherein the adjustment is a time domain circular shift, wherein theparticular DMRS sequence is generated by applying the time domaincircular shift to the base DMRS sequence.
 20. The computer-readablemedium of claim 19, wherein the adjustment further includes anorthogonal mask, wherein the particular DMRS sequence is generated byfurther applying the orthogonal mask to the base DMRS sequence appliedwith the time domain circular shift.
 21. The computer-readable medium ofclaim 15, wherein a length the base DMRS sequence is half of a length ofthe particular DMRS sequence, wherein the adjustment is an time domainrepetition and an orthogonal mask, wherein the particular DMRS sequenceis generated by repeating the base DMRS sequence and applying theorthogonal mask to the repeated base DMRS sequence.